I was asked a very interesting question the other day. "Why is usability so hard? Isn't it just common sense?"

This is a great question, and one that took me a long time to be able to answer. My difficulty was not because usability is actually easy, but because it can be hard to approach that question properly. The answer is complex and detailed, but like all good things, the basic idea behind it can be explained simply. It's that simple answer that eluded me until now. The problem is partly in the questions. Usability testing is relatively simple and straightforward. The first question should really be "why is it so hard to build usable sites?"... [more]